Serum Syndecan-1: a potent prognostic biomarker for transplant outcomes

Introduction: Post-transplant-associated complications arising from endothelial injury, such as sinusoidal obstruction syndrome (SOS) and transplant-associated thrombotic microangiopathy (TA-TMA), are associated with high mortality rates following hematopoietic stem cell transplantation (HSCT). Syndecan-1 (SDC1), a cell-surface proteoglycan released into the circulation upon endothelial damage, is a potential biomarker for vascular integrity. We previously demonstrated that elevated serum SDC1 levels were associated with disease severity and poor prognosis in patients with COVID-19. Methods: This prospective study investigated whether longitudinal serum SDC1 kinetics could predict early mortality in HSCT recipients; serial blood samples were collected from 130 patients undergoing hematopoietic stem cell transplantation (HSCT), from the day of HSCT through day 28 post-transplant, to investigate whether serum SDC1 levels could serve as a predictive marker for early mortality within 100 days after HSCT. Notably, serum SDC1 levels at Days 0, 14, and 21 after HSCT were significantly higher in patients who died within 100 days than in those who survived beyond Day 100. Conclusion: These findings suggest that serum SDC1 has the potential to predict early post-transplant mortality and warrants further validation in larger prospective studies.